Smoke From Canada’s Wildfires Darkens Skies Across Northern U.S.

A smoky haze floated over a wide swathe of the northern United States on Tuesday from Canada, where hundreds of wildfires were blazing, triggering air alerts from Minnesota to Massachusetts.

In Ontario, a layer of haze blanketed parts of Ottawa and Toronto, where Canadian officials warned residents about the poor air quality, as smoke floated over portions of New York State and Vermont. All of New York City was under an air quality alert on Tuesday because of the smoke; by the afternoon, the Manhattan skyline was obscured by hazy skies.

More than 400 active wildfires were burning in Canada on Tuesday, according to the Canadian Interagency Forest Fire Centre, exacerbating an already active wildfire season that is only expected to worsen. More than 200 of the fires were burning out of control, the agency said.

In eastern Canada, Quebec was most affected by wildfires as of early Tuesday afternoon, with more than 150 active blazes across the area, according to the fire agency. Residents in some areas were being encouraged to shut their windows and doors, local officials in Quebec said.

Videos and images showed some fires blazing for miles, sending dark smoke plumes billowing into the sky.

At a news conference on Monday, Prime Minister Justin Trudeau said he was in contact with local officials across Canada about the fires.

“This is a scary time for a lot of people,” Mr. Trudeau said.

As of Monday, an estimated 26,000 people across Canada had been evacuated from their homes because of wildfires, Bill Blair, Canada’s minister of public safety, said at the news conference.

“The images that we have seen so far this season are some of the most severe ever witnessed in Canada,” Mr. Blair said.

Many Canadians who have had to evacuate in recent days had just a few hours to pack before fleeing their homes, Mr. Trudeau said.

“When people lose their homes, they don’t just lose a roof and their possessions,” Mr. Trudeau said. “They lose a special place where they saw their children grow up, where they built a life for themselves. This is incredibly difficult and heartbreaking.”

Bands of smoke from the wildfires shifted southward across the border on Tuesday, creating hazy skies and prompting the U.S. National Weather Service to issue air quality alerts for parts of the upper Great Lakes and the Northeast.

Large swaths of Minnesota were under an air quality alert through the evening on Tuesday, the Weather Service said, as light winds pushed smoke from wildfires in Quebec across Minnesota. Smoke also moved into the state from Lake Superior.

Weather officials warned that people more sensitive to poor air quality, such as people with lung disease and heart disease, children and older adults, should limit certain activities outdoors.

Air quality alerts were also in place in New York City and in multiple counties in upstate New York through midnight. Mayor Eric Adams of New York said on Twitter that New Yorkers with heart or breathing issues should limit their time outside to “to the absolute necessities.” Similar alerts were issued for parts of Connecticut, Massachusetts and Vermont.

Toronto and New York City briefly ranked among the top 10 major cities with the poorest air quality on Tuesday, according to IQAir, a technology company that tracks air quality and pollution around the world. Historically, Toronto and New York City do not rank in the top 3,000 cities with the worst air quality, according to IQAir.

Poor air quality was expected to continue into Wednesday for much of upstate New York and the New York City region, according to the New York State Department of Environmental Conservation.

Satellite images of North America on Tuesday showed light brown smoke streaming south from the fires. The smoke appeared to be particularly thick over portions of Quebec, Ontario and New York. Hazy conditions could also reach as far south as the Carolinas.

In addition to the poor air quality, smoke from the wildfires could a create vivid, reddish sunset, similar to what New Yorkers saw last month when smoke from Canadian wildfires drifted south.

John Cristantello, a meteorologist with the Weather Service in New York, said that such sunsets and poor air quality could persist this summer if wildfires continue to burn in Canada.

Mr. Blair, the public safety minister, said that hundreds of soldiers had been deployed across Canada to help with firefighting efforts. Other government agencies were on standby if wildfires damaged critical infrastructure, Mr. Blair said.

Mr. Trudeau said on Monday that forecasts indicated that “this may be an especially severe wildfire season throughout the summer.”

To date, there had already been more than 2,200 wildfires in Canada this year, according to the country’s fire agency.